How often have you gotten an email from a troubled prince, a long-lost relative or a distressed damsel, and instantly sent it to the trash? You know the type of message I’m talking about — a typo-filled pile of run-on sentences which offers you riches in exchange for your help. You probably immediately recognize such notes to be some sort of scam … and as do most people.

So why don’t scammers try to write better, more convincing emails?

Because the lousy ones help them pick out the best targets.

Computerworld’s Rothan Pearce calls attention to a research paper by Cormac Herley, principal researcher at Microsoft Research’s Machine Learning Department, which explains how it all works. The paper’s pretty full of math and will likely give you a headache — or require you to re-read it several times for comprehension — but it boils down to this: “By sending an email that repels all but the most gullible the scammer gets the most promising marks to self-select.”

Emails which are poorly written or identify the sender as a resident of Nigeria — a country often associated with certain scams — weed out the skeptics, the people who wouldn’t easily believe that a stranger would send them millions in exchange for a small fee.

This means that the scammers can focus on the folks who are most likely to suspend disbelief and proceed to lure them into their schemes (which is an effort intensive process). Using transparent emails for the initial contact keeps the scammers from wasting time communicating with potential victims who’d see through their lies before it’s too late.

So what lesson can we take from this? That we shouldn’t underestimate the folks who are looking to scam us. There’s definitely reason to their apparent madness.